In the central Ligurian Basin, Western Mediterranean Sea, dense water formation occurs in winter so that near-surface stratification displays a marked seasonality. Consequently, kinetic energy spectra from the surface to intermediate depths are entirely different in summer and winter. In summer, the spectra show a peak near the local inertial frequency (f). The polarization of currents in the internal gravity wave frequency (sigma) band (f < sigma < N, N the buoyancy frequency) resembles internal wave theory (for N >>f). In winter, however, no significant near-inertial (or any other) spectral peak is observed and motions are not polarized at any frequencies, whatever the observation depths. With respect to the energy levels observed in summer,... |